The present invention relates to a magnetic disk recording apparatus, and more particularly, to a circuit for controlling the write current applied to magnetic heads (i.e., data transducers) to write data on magnetic disks of the magnetic disk recording apparatus.
A magnetic disk recording apparatus, such as a hard disk drive (HDD) or a floppy disk drive (FDD), is generally used as an auxiliary memory device for a computer system. A hard disk drive (HDD) usually has the capacity to stably store a large amount of data, and enables rapid access to stored data. As the writing density of magnetic disks for hard disk drives (HDDs) is continuously increased in order to increase data storage capacity, the magnetic heads must operate with a high degree of precision and therefore be very sensitive to a write current. Accordingly, the magnitude of the write current applied to the magnetic heads is a critical factor in the performance of the hard disk drive (HDD). For example, an increase in the magnitude of the write current causes an increase in the amplitudes of signals picked up by the magnetic heads when reading data from the disks.
Several references discuss the subject of write currents in a magnetic disk recording apparatus. U.S. Pat. No. 5,550,774 entitled Current Setting Circuit To Provide A Write Current To A Recording Apparatus issued to Watanabe et al is one such reference. In Watanabe et al. 5,550,774, a write current setting circuit for a magnetic recording apparatus employs a reduced number of integrated circuit (IC) pins by enabling an increase of the integrated circuit (IC) pins accompanying an increase in the number of modes to be kept to a minimum. According to these principles, when six external resistance elements are used to generate a sub-mode correction current, (2.times.n) modes can be set by (n+1) pins of the integrated circuit. While this type of conventional art provides merit in its own right, I note that it fails to address specific problems that plague the art. For example, I note that it fails to recognize that the amount of write current employed should be varied for each of the different magnetic heads and disks of a hard disk drive (HDD).